1. Technical Field
The present invention is directed to a method and apparatus for affixing a safety line to dental restorations and appliances. More particularly, the invention relates to a method and apparatus for temporarily bonding a safety line directly to a dental restoration or appliance so as to prevent the accidental ingestion or aspiration of restorations or appliances during the fitting or removal stage while still allowing the subsequent removal of the line when restorations or appliances are permanently affixed in the mouth, or removed from the mouth, without alteration or damage to the dental restorations or appliances.
2. Description of the Prior Art
Dental patients are placed in a reclined position in order to facilitate dental operating procedures. With patients in this position there is a high probability that objects placed in the patient's mouth by a dentist will fall toward the back of the mouth resulting in the aspiration or ingestion of the object.
This occurrence has potentially serious consequences, and has been well documented. Location and extraction of the dental object is costly and inconvenient in the best of circumstances, and has on occasion been fatal. As such, the fitting of dental restorations and appliances in the patient's mouth by a dentist poses substantial danger to the patient.
The dental profession has come to realize the danger posed to the patient by these objects and various methods have been advocated to prevent aspiration or ingestion, however, most have some drawbacks. Some experts advocate working with the patient in an upright position, but most modern practitioners find it extremely difficult to do so. The use of a rubber dam is suggested but it is impossible to perform many of the fitting procedures adequately with a rubber dam in place. Alternatively, gauze throat packs have been advocated but these are extremely uncomfortable and poorly tolerated by many patients. As such, these means though available are only partially effective, are often not employed because of time constraints, or significantly add to the discomfort of the patient.
The most effective means currently available to the profession to prevent the aspiration or ingestion of dental objects is to tie a piece of floss, string, or monofilament safety line to the appliance prior to introduction into the mouth. In this manner, even if the device does fall to the back of the throat, it can be easily retrieved by the dentist or assistant. Items such as dental bridges, endodontic files, and many intraoral instruments have retentive areas available which allow the securing of some type of safety line. Such retentive areas are often times a natural result of the design of the appliance itself as would be the case with a dental bridge. In other instances, a retentive area has been specifically designed into the instrument by the manufacturer.
Many dental objects, however, are smooth-surfaced and have no retentive area whatsoever. This precludes the routine attachment of any type of safety line.
The most common example of an appliance which does not lend itself to being secured with a safety line is an individual dental crown. This appliance poses convex surfaces with no available undercuts or tie-off points. Proper fitting of a crown requires the placement of the appliance on the tooth a number of times to examine its fit and function.
During each of these try-ins, the appliance can easily become dislodged from the tooth by the action of the patient's tongue or can slip from the operator's fingers. Since a safety line cannot be routinely secured, this occurrence has potentially serious consequences.
In addition to individual crowns, modern dentistry utilizes numerous other devices which are smooth-surfaced and provide no retentive undercuts for securing a safety line. Examples of such devices would include temporary crowns, pre-cast endo posts, cast endo posts and cores, and dental implant inserts.
Realizing the potential serious consequences posed by smooth-surfaced dental devices, some experts advocate the placement of retentive undercuts in the device during its fabrication. This retentive undercut is used to secure a safety line during the fitting stage but then must be removed by the dentist either before final cementation or once the appliance is permanently in place.
An example of this type of measure would be to incorporate a retentive button as part of the metal structure of a dental crown. This button is used to secure a safety line during the fitting and cementation stages. Once the device is in place, the dentist must take a cutting instrument and physically sever the retentive button from the crown. This area must then be smoothed and repolished to provide a clinically acceptable restoration.
This method of providing a means of securing dental devices with a safety line has several drawbacks. The fabrication of the button into the metal pattern requires a substantial amount of additional laboratory time. Also, even though the retentive button is available, often times this button is improperly utilized which leads to the risk of losing the device down the patient's throat even though steps have been taken to prevent this very accident.
Additionally, this button itself is a source of danger. During the try-in stage, the button projecting from the surface of the crown is sharp and can lacerate the patient's tongue or oral mucosa. Even more dangerous is the fact that if the object is aspirated or swallowed, this sharp projection protruding from an otherwise smooth dental device, could cause serious internal injury.
Finally, the button is often placed in a position which becomes inaccessible once the device is permanently placed and its removal requires substantial time by the dentist, and exposes the patient to the additional risk associated with the intraoral use of high speed cutting and polishing devices.
Another problem associated with incorporating a retentive button during fabrication is that many dental restorations are constructed of materials which do not permit the placement of such a button. Examples of these types of restorations would include veneers, crowns, and inlays constructed entirely of porcelain.
To date, research would indicate that there is no convenient, universally applicable, economical means of attaching a safety line to dental devices.
Ideally, a method should be available having the following features:
The method should allow the affixing of a safety line to any dental device regardless of the availability of retentive undercuts or tie-off points.
The method should be inexpensive.
The method should provide adequate bond strength between the dental device and the safety line.
The method should provide immediate bond strength between the dental device and the safety line.
The method should not require sophisticated instruments or equipment to achieve its bond.
The method should be reversible in that it produces no irreversible modifications to the dental device.
The method should be available to the manufacturer, the laboratory technician, or the dentist directly.
Ideally, a device should be available having the following features:
The device should be sufficiently strong to adequately retrieve a dislodged dental device.
The device should not interfere with the fitting and functional checks of the dental restoration or appliance.
The device should be inexpensive.
The device should allow for easy manipulation and placement on the dental restoration or appliance.
The device should assist in identifying a specific dental restoration or appliance.
The device should provide sufficient surface area at the bond interface to insure adequate strength between the dental device and the safety line.
The device should be easily removed from the dental restoration or appliance.